The present invention relates to manufacturing techniques for semiconductor devices and in particular to a technology effectively applicable to a method of manufacturing a semiconductor device obtained by placing a semiconductor chip over a die pad of a lead frame and sealing this semiconductor chip with resin.
Japanese Unexamined Patent Publication No. 2004-96022 (Patent Document 1) and Japanese Unexamined Patent Publication Hei 7(1995)-14965 (Patent Document 2) describe that a groove for air vent is formed in part of a lead frame during a molding step.    [Patent Document 1]    Japanese Unexamined Patent Publication 2004-96022    [Patent Document 2]    Japanese Unexamined Patent Publication Hei 7(1995)-14965